In a MIMO communication system, a received signal of each receive antenna is subject to two types of interference: inter-symbol interference (ISI) and inter-channel interference (ICI). ISI is interference of the tail of an earlier signal to a subsequent signal during signal transmission. ICI is adjacent-channel interference caused by a receive antenna receiving a signal from another antenna. To obtain reliable communication performance, in a MIMO system, ISI and ICI of a received signal need to be eliminated at a receive end.
An existing equalizer in a microwave MIMO system includes a plurality of sets of parallel-connected finite impulse response (FIR) transversal filters and a signal combination point. Each FIR transversal filter performs equalization filtering on received signals of an antenna, and adopts the equalization principle to eliminate ISI from each tributary signal. Moreover, while performing the equalization, a set of FIR transversal filters adjusts a weight coefficient for outputting the received signals of each antenna, thereby achieving reverse elimination of ICI by using the weight coefficient during combination and eliminating ICI at a signal combination point.
By adopting the foregoing existing equalizer, elimination of the ICI is implemented when each FIR transversal filter adjusts a weight coefficient to approximate an inverse matrix coefficient of a MIMO channel. An algorithm for approximating an inverse matrix coefficient of a MIMO channel by adjusting the weight coefficient is affected by the singularity degree of the MIMO channel. Therefore, the foregoing method is only applicable to a microwave MIMO system with a sparse antenna array. When applied to a microwave MIMO system with a compact antenna array, the method has a poor effect in eliminating ICI and transmission performance severely deteriorates.